The present invention relates to a semiconductor unit of the type including at least two semiconductor elements which are fastened in a housing to a metallic base plate in an electrically insulated and thermally conductive manner and provided with current conductor members which also form current terminals and which are contacted under the influence of pressure exerted by spring bodies.
German Utility Model Patent No. 7,512,573 discloses a semiconductor rectifier arrangement in which two semiconductor rectifier elements are fastened in electrical series connection, with their connecting components electrically insulated and thermally conductive to one side of a metallic base plate. The arrangement is embedded in an insulating mass in a plastic housing. The rectifier elements are connected together by a connecting conductor designed to form a third current conduction terminal in line with the other two current conduction terminals and located at one end of the resulting row of three current conduction terminals. The outermost current conduction terminals in said row each are fastened to the associated rectifier element on a conducting layer and, via this layer and an insulating intermediate disc, together to the base plate.
Other prior art semiconductor rectifier arrangements are provided with rectifier elements which are pressure contacted in recesses of the housing and are encased in an insulating mass.
These prior art units have various drawbacks. For example, solder contacting of the rectifier elements is a complicated procedure. When the elements are pressure contacted and embedded in an insulating mass, the rigid encapsulation of the contacting system, which is intended to exhibit an elastic behavior during use, makes the structure susceptible to malfunction. Moreover, the process steps of soldering or encapsulating in the insulating mass, respectively, may adversely influence the electrical properties. Additionally, mechanical stresses due to differences in thermal expansion of adjacent materials frequently result in a reduction of quality. If the parameters of one or more rectifier elements should deteriorate, there is no chance for replacement so that the arrangement must be downgraded regarding its parameters or becomes unusable.
Moreover, none of the prior art structures meets the demands of manufacturers who wish to repeatedly monitor the assembly stages without having to destroy semifinished arrangements and to be able to consider technically relevant factors in a desired manner. None of the prior art embodiments provides a design with selectable electrical orientation of the semiconductor elements. Finally, rectifier arrangements with current conducting terminals arranged in a row cannot always be used universally since they are limited to only one connecting plane.